26.4.5.3 The format_bytes() Function

Given a value in bytes, converts it to human-readable format
and returns a string consisting of a value and a units
indicator. Depending on the size of the value, the units part
is bytes, KiB
(kibibytes), MiB (mebibytes),
GiB (gibibytes), TiB
(tebibytes), or PiB (pebibytes).